1. Field of the Invention
The invention relates to a projecting pole rotor for a rotary electric machine and to a rotary electric machine comprising such a rotor.
The invention relates more particularly to a rotor of a rotary electric machine, in particular to an alternator or alternator-starter for a motor vehicle, comprising:                a rotor shaft which is designed to be mounted such that it can rotate about its axis;        a stack of laminations which is mounted coaxially on the rotor shaft and which comprises at least two radially projecting poles;        a field coil which is wound around each pole so that axial end portions of the coil, referred to as coil ends, project axially with respect to each radial outer axial end face of the stack of laminations;        two plates for supporting the stack of laminations, which plates are arranged axially on either side of the stack of laminations so that the inner radial faces of the plates bear against the radial outer axial end faces of the stack of laminations, housings being provided in the inner radial face of each plate to receive the coil ends.        
2. Description of the Related Art
The documents WO-A-02/054566 and FR 2 856 532 show a typical prior art rotor.
In this type of rotor, the application of a voltage to the coils causes them to heat up. If the field coils are heated too much, this may be detrimental to the safety and efficiency of the machine.
This document proposes to cool the coils by providing an opening in the plates for supporting the stack of laminations, so as to leave the coil ends in contact with the air.
Furthermore, a fan is arranged on the outer radial face of each plate so as to move the air inside the machine when the rotor is rotating.
However, the blades of the fan are far away from the openings, thus preventing the air from circulating at the point of contact with the coil ends. The stagnant air contained in the opening between the fan and the coil end forms an insulating layer which prevents the heat from being dissipated. The coils are therefore not cooled in an optimal manner.
What is needed, therefore, is an improved system and rotor that improves cooling.